My car in the reflection of a close buddies. He likes his car, but if you were to compare how much each of has spent on maintenance, his list is much longer. Still low miles for its age too.
Bmws, particularly ones made before the mid 2000s are pretty good cars, a modern one would be the last car is want to own along with a Hyundai or a Kia. You won't die if you buy the z4, nor feel that you made the wrong choice (unless a Porsche passes by.)